Pegjs online can't parser parser.pegjs

On https://pegjs.org/online if we copy and paste https://github.com/pegjs/pegjs/blob/master/src/parser.pegjs there we get this error:
```
Line 78, column 21: Expected "!", "$", "&", "(", ".", character class, comment, end of line, identifier, literal, or whitespace but "@" found.
```
With all examples from https://github.com/pegjs/pegjs/tree/master/examples it parses OK.